Crustaceans have an exoskeleton, meaning they don't have a spine to protect their nervous system, just their carapace. When you dissect a crab or lobster you can see their ventral nervous system easily (once you remove their organs and such):

Wednesday, October 20, 2010

What did you do to celebrate Alaska Day? I staged chromatophores on shrimp with the Biology 310 lab I'm TA-ing! Exciting, right?

the carapace of a shrimp (Pendalus sp.) with its chromatophores (the orange starbursts)

Chromatophores are pigment-containing cells that generate shell color for crustaceans. Some crustaceans can change color to match their backgrounds (cephalopods are also awesome at this!). And, like all things interesting (to me), chromatophores are under hormonal control!

To stage the chromatophores, the students looked at shrimp under dissecting scopes and determined how dispersed the pigments were. A dot is considered stage 1, but the more branching and dispersed the chromatophore, the greater its stage (with 5 being the most dispersed).

more pretty chromatophores! I'd stage these as 3's and 4's

Pineapples!!!! Really, chromatophore pineapples!!!!

These were from Kevin's physiology project last year.

I'm not sure how I'd stage these, but probably stage AWESOME!

Not specifically Alaskan, but fun nonetheless. Still, let's take this time to appreciate some of the many wonderful Alaskan crabs:

Wednesday, October 13, 2010

Jon is, well, he's Jon. He listens to techno while processing data, speaks Russian, and, like any self-respecting born-and-bred Alaskan, wears shorts in December. He also has the wonderful distinction of working with crabs, albeit in the form of years of data, and as such is our next interviewed grad student!

I am examining possible recruitment controls for Tanner crab in the eastern Bering Sea region using 2 different methodologies. The first employs generalized least squares (GLS) based regression analyses to compare estimated recruitment to the 30-50 mm carapace width (CW) size class against various biophysical parameters measured in previous years. The second employs regional ocean modeling system (ROMS) hydrodynamic modeling to attempt to model advection and subsequent settling patterns of larval crab, with these then being compared against data on the aforementioned biophysical factors and recruitment index using geostatistical methods present in ArcGIS.

blue king crab from the Chuckchi benthos (see the Chionoecetes too?!?)

2. As a modeler working with YEARS of data, what is a challenge you’ve had to overcome and how did you do it?

One of the major proposed recruitment controls is wind vector, which drives directionality of Ekman transport. Unfortunately my data for this came in the form of 60 192*94*365 data matrices — just to extract the data in R required learning to look at several 2D arrays and then mentally project those into a 3D matrix to grasp the internal addressing system used by the dataset, which was necessary to subset the specific data that I wanted. For someone used to working primarily with Excel spreadsheets, this was…….painful.

3. You don’t work directly with live crabs, but you have worked at sea and in the field. What’s the craziest thing you’ve seen/done?
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Gerstle River

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Craziest thing I’ve done? Dear god, that’s a hard one….off the top of my head, back in the summer of 2007 I was part of a US Fish and Wildlife team that was sent into the old Gerstle River training area just out of Delta Junction. This area was used in the 1950’s and 60’s by the army to test chemical weapons, including nerve agents such as VX and sarin, though it was subsequently closed and decontaminated. Long story short: we were getting anecdotal reports of growth abnormalities in the local populations of game and fish that could have resulted from exposure to the agents or byproducts of their decomposition, suggesting that perhaps something had been missed during the cleanup effort. To confirm/disprove these reports my team was sent in to survey local wildlife populations for any indications of abnormalities and to look around for any signs of old munitions. Problem was our only protection was the following advice: “If you see something that looks like a bomb or an old metal barrel, immediately go the opposite direction for at least 500 ft, and if at any point you experience difficulty breathing for any reason, do not be afraid to call 911”.

I was actually rather tempted to take a red shirt out with me, but I didn’t think my boss would think that it was funny. And no we did not find anything, which I do not actually regret….well, except for a ginormous mutant wasp-thing, that the boss didn’t think was conclusive evidence of anything.

Girstle River gigantor mutant wasp thing

Craziest thing I’ve seen: in the summer of 2008 I was part of an American team participating in the International Polar Year cruise of the T/S Oshoro Maru, a research and training vessel operated by the University of Hokkaido. On the last night of the cruise one of the Japanese students on board decided to try his hand at deep sea fishing, and, well, to say he caught a big one would be a bit of an understatement—he snagged a full grown humpback whale. It was of course subsequently released. [Blogger's note: The guy was using a pink pixee! True story.]

T/S Oshoru Maru -- don't tell Sea Shepard!

4. You are a scientific diver. How long have you been diving and what inspired you to start?

I’ve been diving since the fall of 2005, and as for what inspired me, well, when I was a kid I was something of a tidepooler and was *very* interested in the various organisms I found. Thing was, I knew I was only seeing a snapshot of their life cycle and that it was not representative of what things were like when the tide was in. Additionally, I was extremely curious about what things were like in the subtidal and deeper regions, and what lived there. Then when I was 8 it happened: the local NBC affiliate began running old episodes of a show produced by Jacques Cousteau and I was introduced to SCUBA, leading about 3 seconds later to a “EUREKA!” moment.

5. What is your favorite piece of crab paraphernalia?

That would be a picture I took last winter of a very large Tanner crab molting.